The barren aqueous solution, called raffinate, can be pumped back to be injected or sprinkled over the raw ore once its acidity is restored.
The partially loaded organic then passes on to two other mixer-settlers where it counter-currently contacts the other half of the leach solution stream, producing another raffinate stream and loaded organic.
They have a steeply rising and sharply bowed distribution isotherm for extraction which allows very low raffinates and high percentage recoveries to be achieved with fewer stages in the low aqueous copper range.
The two raffinates are similar in copper content, but copper recovery is approximately 6-7% lower than that of a conventional 2 + 1 plant for the same organic extractant concentration.
Additionally, high concentration extractant organic entrainment in aqueous from E1 is caught in E2 and is substituted by entrainment of the lower concentration E2 loop organic in the leaving raffinate.